Endoscopes are widely used for a variety of medical procedures. To improve their performance, endoscopes have been optimized in various ways to best accomplish their purpose. Examples of specialized endoscopes include angioscopes, colonoscopes, bronchoscopes, and arthroscopes.
One of the medical procedures that may be performed using an endoscope is obtaining a biopsy sample. FIG. 1 shows a conventional endoscope assembly 10 used for obtaining a biopsy sample. The endoscope assembly 10 includes an endoscope 20 having an elongated insertion tube 22. The insertion tube 22 may be rigid, partially flexible, or entirely flexible. The insertion tube 22 includes a distal portion 24 that may be inserted into a body cavity of a patient (not shown), and a working end 26.
The endoscope 20 includes a headpiece 28 that remains external to the patient during a medical procedure. In the embodiment shown in FIG. 1, the headpiece 28 includes an eyepiece 30 for viewing the scene through a viewing lens 31 at the working end 26 of the insertion tube 22, a pair of bending control knobs 32 for manipulating the position of the distal portion 24 of the insertion tube 22, and a pair of fluid control actuators 34 for controlling the flow of fluids through tubes 36 to (or from) the working end 26. Endoscopes 20 of the type generally shown in FIG. 1 are described more fully, for example, in U.S. Pat. No. 5,931,833 issued to Silverstein, U.S. Pat. No. 5,483,951 issued to Frassica and Ailinger, and U.S. Pat. No. 4,714,075 issued to Krauter and Vivenzio, which patents are incorporated herein by reference. Representative commercially-available endoscopes include, for example, video or fiberoptically-equipped sigmoidoscopes, bronchoscopes, nasopharyngolaryngoscopes, colonoscopes, and gastroscopes.
As further shown in FIG. 1, the endoscope assembly 10 includes a sheath 40 that encapsulates the insertion tube 22 to prevent at least part of the insertion tube 22 from being soiled during the medical procedure. The sheath 40 may be flexible to allow unrestricted bending of the flexible portion of the insertion tube 22, or may be relatively rigid. In the depicted embodiment, the sheath 40 includes an enlarged fitting portion 42 that fits over an engagement portion 44 of the headpiece 28, and a channel 46 having a proximal end 48 that projects outwardly from the sheath 40 proximate the headpiece 28. Sheaths 40 of the type generally shown in FIG. 1 are described more fully, for example, in the above-referenced patent to Frassica and Ailinger.
During a medical procedure, a surgical instrument 50 having a biopsy sampling device 52 is inserted into the proximal end 48 of the channel 46, and slid through the channel 46 until the biopsy sampling device 52 emerges at the working end 26. A variety of biopsy sampling devices 52 are known, including forceps (e.g. U.S. Pat. No. 5,820,630 issued to Lind), loop and cup devices (e.g. U.S. Pat. No. 5,417,697 issued to Wilk et al., U.S. Pat. No. 5,741,271 issued to Nakao et al.), and cylindrical cutting devices (e.g. U.S. Pat. No. 4,651,753 issued to Lifton). In alternate embodiments, the biopsy sampling device 52 may be inserted through one or more channels that are integrated into the insertion tube 22 of the endoscope 20, as described, for example, in the above-referenced patents to Silverstein and Nakao et al. After a biopsy sample is obtained, the biopsy sampling device 52 containing the biopsy sample may be withdrawn through the channel 46, or alternately, the entire insertion tube 22 may be withdrawn from the patient's body with the biopsy sampling device 52 remaining in position near the working end 26.
Although desirable results may be achieved using conventional endoscope assemblies, some drawbacks exist. For example, in some fields of medicine, the majority of physicians do not own an endoscope having built-in channels due to the prohibitively high cost of such instruments. Although sheaths having channels may be used, some biopsy sampling devices are too large to be fitted through the conventionally-sized channels (typically 2 mm in diameter) of existing endoscope sheaths.
Furthermore, relatively new diagnostic techniques are available that allow for testing for the presence of cancer by testing cells that are obtained by brushing a mucosal surface using a biopsy brush. In some areas of the body (e.g. the mouth), a target surface may be readily accessible using an ordinary biopsy brush without the use of specialized tools. Other areas of the body (e.g. the nasopharynx or the esophagus), however, may not be reachable using an ordinary biopsy brush. Existing endoscope assemblies severely limit the sizes of biopsy brushes that may be employed due to the relatively small sizes of the channels, making the task of obtaining a suitable sample using a biopsy brush difficult or virtually impossible.